Histologic Characteristics and Clinical Courses of Primary Viral Pneumonia Other than COVID-19

Objective To clarify both the histologic changes in primary viral pneumonia other than COVID-19 and whether patients with severe lung injury (SLI) on biopsy specimens progress to severe respiratory insufficiency. Methods Patients with primary viral pneumonia other than COVID-19, who underwent lung tissue biopsy, were retrospectively studied. Patients Forty-three patients (41 living patients and 2 autopsied cases) were included in the study. Results Nine patients had SLI, whereas most of patients who recovered from primary viral pneumonia showed a nonspecific epithelial injury pattern. One patient underwent a biopsy under mechanical ventilation. Two of 8 (25.0%) patients on ambient air or low-flow oxygen therapy progressed to a severe respiratory condition and then to death, while only 1 (3.1%) of 32 patients without SLI progressed to a severe respiratory condition and death (p=0.096). The proportion of patients who required O2 treatment for ≥2 weeks was higher in patients with SLI than in those without SLI (p=0.033). The 2 autopsy cases showed a typical pattern of diffuse alveolar damage, with both showing hyaline membranes. Non-specific histologic findings were present in 32 patients without SLI. Conclusion Some patients with SLI progressed to severe respiratory insufficiency, whereas those without SLI rarely progressed to severe respiratory insufficiency or death. The frequency of patients progressing to a severe respiratory condition or death did not differ significantly between those with and without SLI. The proportion of patients who required longer O2 treatment was higher in SLI group than in those without SLI.

[Pandemic influenza A (H1N1)v in the intensive care unit: what have we learned?]

The characteristics of pandemic influenza 2009 differ from those of seasonal influenza. In Australia-New Zealand the number of admissions to the intensive care unit (ICU) increased by 15-fold in the southern winter. We compared the characteristics of the Spanish series of the first ICU admissions in July with those of series published in Canada and Australia-New Zealand up to October 2009. Unlike the situation in Spain, only half the admissions in Canada and Australia-New Zealand were due to primary viral pneumonia but bacterial pneumonia was much more frequent. In all series, young people, many of whom had no comorbidities, were the most frequently affected population. The most common comorbidities were obesity, chronic pulmonary disease, pregnancy and heart disease. Diagnosis through reverse-transcriptase polymerase chain reaction can have a false-negative rate of 10%. Shock and acute renal insufficiency were more frequent in the Spanish series. A total of 10-30% of patients required ICU admission and 6 of 10 patients required mechanical ventilation with a high frequency of failure of non-invasive ventilation (75%). Mortality was similar among the series (14-25%) but was higher in patients requiring mechanical ventilation (30%). Early oseltamivir administration (< 48h after symptom onset) has been associated with better outcome. Therefore, early administration of this drug in patients with risk factors or those who, although free from risk factors, show clinical progression, could reduce ICU admissions and mortality.